Standards I can compare and contrast the parts of a wave. ( ) I can differentiate between transverse and longitudinal waves. ( )

Waves and Energy Wave – a disturbance that transfers energy through matter or space Example: Throwing a pebble into a pond Where the pebble hits the water, waves move outward from that spot Energy from the pebble’s splash causes the water to move up and down as the wave passes. This is known as a disturbance All waves are disturbances that carry energy from one place to another

Waves and Energy Waves transmit energy but not matter

Waves and Energy Energy travels through matter but the wave does not transmit it In other words, the object moves up and then back down to its original position just as you did when doing the wave

Waves and Mediums Many waves require a medium in order to transfer energy (mechanical waves) Medium – a material that is disturbed by a wave Examples: air, water, or solid objects When travelling through a medium, a wave displaces the particles of the medium The particles do not travel with the wave They move up and down or back and forth and when the wave passes return to their original resting position

Waves and Energy Example: Stadium wave Some waves, such as light and radio waves, do not require a medium Electromagnetic waves – transfer energy through empty space Example: sunlight

Characteristics of a Wave Amplitude – distance from the midpoint of a wave to its top (crest) or its bottom (trough) A water wave with high amplitude is a tall wave A sound wave with high amplitude causes you to hear a loud sound

Characteristics of a Wave Wavelength – distance from any point on a wave to the identical point on the next wave Crest to crest or trough to trough Waves with short wavelengths transfer more energy than waves with long wavelengths

Characteristics of a Wave Frequency – number of waves that pass a given point in one second Frequency and wavelength are inversely related When one increases, the other decreases Unit of frequency is the hertz (Hz) 1 hertz = 1 wave per second A sound wave with high frequency makes a higher- pitched sound than a sound wave with low frequency

Kinds of Waves Waves are classified as either transverse or longitudinal This is based on how each kind of wave is transmitted Transverse wave – particles of the medium vibrate perpendicular to the path of the wave Example: ocean wave A transverse wave consists of crests and troughs

Kinds of Waves Longitudinal wave – particles of the medium vibrate parallel to the path of the wave Example: sound wave Longitudinal waves are made up of compressions and rarefactions Compression – part where the particles are pushed together (similar to crest) Rarefaction – part where the particles are spread apart (similar to trough)

Lesson Review Which of the following is NOT a medium? A. Space B. Air C. Water D. Wood

Lesson Review A wave’s amplitude is A. The distance from the resting point to a crest or trough B. Distance between the crest of one wave and the crest of the next C. Distance the wave travels in one second D. Number of waves that pass a given point in one second

Lesson Review What do waves transfer? A. Matter B. Energy C. Water D. Particles

Lesson Review Picture a tub filled with water and a toy boat floating on the water. You plunge your fist into the water, next to the toy boat. What will happen to the boat? A. It will travel to the other end of the tub B. It will stay completely still C. It will travel closer to your fist D. It will bob up and down

Lesson Review Which part of a transverse wave is similar to a compression in a longitudinal wave? A. Crest B. Trough C. Midpoint D. Particle